Fluid fuel valve and flue damper control system for furnaces



Jan. 9, 1951 A. L. PALMER 2,537,082

FLUID FUEL VALVE AND FLUE DAMPER CONTROL SYSTEM FOR FURNACES 2 Sheets-Sheet l Filed Aug. 25, 1947 ma M/@Mggwww IA. AFLUID yFUEL VALVE AND FLUE DAMPER CONTROL SYSTEM FOR FURNACES L. PALMER Jan. 9, 1951 Filed Aug. 25, 1947 2 Sheets-Sheet 2 INVENTOR. /lva Z. Palmer Patented Jan. 9, 1951 OFFICE FLUID FUEL VALVE AND FLUE DAMPER CQNTROL SYSTEM FOR FURNACES Alva L. Palmer, Bayside, N. Y. Application AugustZS, 1947, Serial No. 770,337

`The present invention relates to a 'control system for iiuid fuel-fired furnaces and a flue damp-, er which is suitable for use therein; and the present application is a continuation-impart of my co-pending application S. N. 454,648, filed August 13, 1942, Which-application is now abandoned,V i LA general object of the inventionis the provision of such a control system which is of simple construction and readily adapted to economical commercial production and installation, Vwhich efficiently conserves fuel consumption, effectively avoids undesirable losses of heat, may be eniciently employed as a back draft diverter for gaseous fuels, and which in operation avoids the development of conditions which might tend to impair the health and endanger thelives of occupants of buildings equipped with heating sys- ;,emsinclusive of apparatus of the present invenion.` Y .Y

A more specific object of the present invention is. to provide such a control system characterized by the provision of a flue damper in the exhaust flue between a furnace and a chimney which is mechanically operated in an efficient automatic manner so that when the fuel supply to the furnace is shut off communication between the furnace and chimney and between chimney and furnace room is also effectively reduce-d. to a heat-conserving minimum, with such simultaneous automatic control of `fuel,

valving as and flue'damper apparatus being attains`^ in a simple manner through theoperatio-n of means positively mechanicallyinterlocking the two together-whereby fuel cannot be supplied to the furnace when the flue is closed by the damper. i v Y Another object cf the invention is the provision of such a control system wherein fuel valving means and flue damper apparatus are soumechn nically interlcclied in a positive manner as to assi' e that failure in service of any parts, however remotely possible, will not tend to create unsafe conditions. y

An additional object of the invention is the provision in, such controi system of ashut-oif valve in c fuel supply conduit leadingA to the furnace a d a damper means for the exhaust flue beta1-eer Vfurnace and a chimney, with anI autornatically-contrclled motivating' unit for substantially simultaneously opening and closing the dam' r and the fuel valveby mechanical means di ctly connected to the damper plate thereby eliminating the possibility of the damper being closed during supply of fuel to the furnace through failure of intervening linkages ormechanisi is at the damper such as crank arms, etc.

A further object of the invention is the provision of a damper unit for the exhaust flue be-` tween a furnace and a chimney which is characterizediby anexhaust space or compartment 5 Claimant" (Cl. 110-147) lil forconnection to a chimney and a lead-in space or compartment for connection to a furnace with partition wall means dening those spaces or compartments from each other and having a damper opening therein whereby a shut-off damper, plate may belifted to a positionvsub stantially closing the damper. opening by means mounted directly thereto. which whenretracted pulls and/or permits the damper plate to fall by forceA of gravity to an open position therebyr effectively eliminating possibility of the damper blocking the flue upon failure o f parts.

, Still another object of the invention is the provision of such a damper unit which permits inline mounting of sections of flue pipe leading `to and from it without undue interference by with fuel valving means, showing the damper in'v overhead structure and permits effective employment where space is limited.`

A still further object of the invention is ,the provision in such a control system of ilue damper apparatus and fuel valving means having their operating members directly tied together ,byA a rod and the damper `plate thereof mounted directly upon the rod so that both must be sube stantially simultaneously moved to open and closed positions withoutV failure of the damper plate mounting tending to permit ue blockage during supply offuel to the furnace. l jOt-her'objects of the invention will in part be obvious and will in part appear hereinafter.v

AThe invention accordingly comprises thewfeatures of construction; combination of elements and arrangement of parts, which will be exempli iiedin the construction hereinafter set forth and' the scope vof the invention will be indicatedrin the claims.

,"For a fuller understanding of the nature and objects'lof the invention, reference should be had` tothe following detailed description taken inY con-I nection with the accompanying drawings, i which:

Fig. 1 is a diagrammatic elevational view with partsin section and broken away of. a furnace installation featured by the control system of the present invention, the damper and fuel valve ap` paratus being shown ,in closed positions when no' heat is demanded; y Y Y, Y Fig. 2 is an Velevational View, with parts in vertical sectionand broken away, of a modified formV ofthe damper and fuel valveY apparatus of the in 4 stallation shown in Fig. l, showingtheV damperA and fuel valve in open positions resulting from ademand for heat;

Fig.. 3 is-a vertical sectional View of flue damperf apparatus of the present invention in association flue-blocking or closed position and with the' fuel, supply conduitl closed;

Fig. 4 Vis a sectional View taken on line 4 4 Fis-ft i Fig. 5 is a vertical sectional view of the structure shown in Fig. 3 with both the fuel valving meansl and dan in open positions;

6 is a vertical sectional view with parts broken away of a struct c similar to that shown in Figs. 3 and but -vh the employment of a modified form of the flue damper unit of the present invention;

'l is vertical sentional View of a further modified fo in of the i. damper apparatus cf the present invention; and l Fig. t is a vertical sectional view of still another fonn of the flue damper apparatus of the present invention.

Prior to the present invention attempts have been made to conserve fuel consumption and eliminate undue heat losses in furnace installations -by automatic damper control of the exhaust ue between the furnace and the chimney at the same time that fuel supply to the furnace .is automatically controlled. Some such installations are characterized by the provision of back draft diverters or draft hoods in the flue between the furnace and chimney to avoid creation of back drafts through the furnace during momentary down drafts in the chimney and also to provide an emergency ue outlet in the event of chimney stoppage. Also such proposals were made in an effort to ameliorate heat losses from the furnace and from the space surrounding the furnace via the chimney during periods when the burner is not operated and, in the case of employment of gas as fuel, to permit spilling of products of combustion and heated air into the chamber in which the furnace is located, such as a basement, during chimney blockage. One such system is suggested in the United States patent toGilliland No. 2,139,491 of September 20, 1938. Such systems, however, have been found to be commercially impractical due to the fact that many of them have been complicated and have utilized certain electricalor gas-controlled systems wherein failure of damper operating mechanism has resulted in damper-blockage of the flue during supply of fuel to the burner and has in some cases created conditionstending to impair health and endanger life as to make necessary their abandonment. These and other difficulties of the prior art have been efciently eliminated by the present invention.

l In accordance with the present invention a simple control system is provided wherein the burner of a furnace is supplied with a fluid fuel, such as oil, gas or the like, through a conduit having a shut-off valve therein. An exhaust, ue for connection between the furnace and a chimney is provided with a shut-off damper means or plate and in case of employment of gas asa fuel with draft hood or back draft diverter opening. An automatically-controlled motivating unit such as a fluid-operated diaphragm mechanism, a motor unit, or the like, which may be of well known design such as that disclosed in the United States patent to Branche No. 2,037,363 of April 14, 1936, is employed to operate both the damper means or plate and the fuel valve. Interlocking mechanical means, directly connected to the damper means or plate and to the valve, are associated with the motivating or motor unit as to assure substantially simultaneous opening and closing of the damper and fuel valve. This direct connection of the damper plate to the mechanical operating means is free of intervening linkages or mechanisms at the damper, so as largely to eliminate the possi' bility of a disconnect between the damper plate and motor unit during service. In the preferred form, the damper unit is of a type such that the damper unit is lifted to closed position and permitted to fall by force of gravity to open position so as to assure that any possible failure of operating parts will not tend to result in damperblockage of the flue at any time during supply of fuel to the burner. These and other features inclusive of specific structure of preferred embodiments of damper apparatus will be more fully explained hereinafter by reference to the drawings wherein like numerals refer to like parts throughout.

In Fig. 1 is shown a furnace l0 of conventional construction mounted upon a suitable support I I, such as a oor of a basement, and equipped with a conventional type of burner I2, such as that adapted for consumption of gas, and a pilot I3. The burner l2 and pilot i3 are connected to a fuel supply conduit or gas line i4. The conduit ld is provided with a suitable shut-olf valve I5.,

The furnace Ill has its combustion chamber connected to a chimney i6 by means of an exhaust ue l1, through a section i9 provided with a draft opening i8, to serve as a control for the draft through the furnace appliance when connected to the chimney past an open nu'e damper, and also as a back draft diverter, when the iiue damper is open. The section I9 'constitutes a damper unit having a suitable damper plate 2) lixedly mounted, 'such as by welding or the like, on an upwardly extending operating rod 2l. A suitable motivating means, such as an encased electrical motor-operated mechanism 22,

is mechanically connected directly to the damper operating rod 2i such as by means of a laterally turned lower end 23 of the rod slidably receivedv the usual manner in some upper room of the dwelling or building.

`Preferably the -fuel supply conduit i4 adjacent the yvalve i5, such 'as at 26, 26 is suitably supported and held in fixed relation relative to the fiue l by suitable rigid members or straps 21,

' downwardly facing seat against which a valve member 2Q is biased upwardly by a helical spring 3B. The valve member 2S has a stem 3| linked t'o the arm 32 of the encased electrical motordpera'ted mechanism 22 in a well-known manner prisesa casing structure having an exhaust com--v and may be of a structure similar to that disclosed in the above identied Branche Patent No. 2,037,363.

The'damper unit I9, as shown in Fig. 1, compartm'e'nt-S provided with an 'outlet opening deass-esa fined by anexhaust pipe section connected t the chimney I6 and a lead-in compartment 35 having an inlet opening dened by an inlet pipe section 33 connected to the combustion chamber of the furnace I0. The casing has' a draft opening I8 in a wall thereof communicating withv lead-in compartment 35. Partition Wall means 31 in the casing defines the'compartments 33 and 35 from each other and is provided with adamper openi-ng 38 closed off by a damper plate when lifted to the position shown. A strap or bracket 39 is mounted on the casing and may carry an apertured sleeve 4|) reciprocatively receiving lift-rod 2| to guide it in its up and down movement. 1'

AAt'the time the damper plate 20, valve I5 and motivating unit 22 areassembled relative to each other,`the damper plate and the valve member 29 are adjusted to positions relative to eachother so-that when the`valve member is lifted to the valve closing position shownthe damper plate is lifted to flue-blockage position shown. Upon demand by the thermostat unit for additional" heat, the damperl platefe will be lowered by its rod 2| to uncover at least a portion of the damper opening '3B-simultaneously with lowering of valve member 25 by vits stem 3| to open fuel valve I5, both by action of the motivating unit 22, and both'the damper plate and the fuel valve member will be moved or lifted together by the motivating unit to closed positions when demand of the thermostat device for additional heat has been satisfied. This support of damper plate 20 by lift-rod 2| without the presence of any intervening linkage substantially eliminates possibility of failure and "should connection between the lift-rod 2| and the motivating unit 22 fail for an unexpected reason it will be seen that by force'of gravity the damper plate will fall and/or remain in an open position avoiding blockage of the flue at any time including periods when fuel is supplied to the burner.' y l In the above described system, during periods of damper, such as illustrated herein is employed;

In Fig. 2 is shown an example of such an e1nbodiment of the invention.

As indicated in Fig. 2, the damper unitl 9 may comprise a casing having therein partition means |31 vdividing its chamber into an exhaust com-V-v partment |33 and a lead-in compartment |35. A section |34 of the exhaust fiue is let in through a lwall of the casing for communication with exhaust compartment |33 and is intended to be connected to the chimney and another section |36 of the ilue is let in through another wall of the casing for communication with the lead-in comof shut-off of fuel supply the flue IIv will be subwasted. This direct mechanical interlocking be#V tween the damper plate and the fuel supply valve prevents the ue from being blocked at anytime during supply ofy fuel to the burner.

If fuel oil is to be used it will be understood that the apparatus should be mdied'to avoid spilling into the air surrounding the furnace any obnoxious gases of combustion. Thus the usual" one-'way butterfly valve maybe employed to closeY a draft opening against reverse flowof gases with that 'draft opening serving to control thedraft through the furnace appliance when connectedl to the chimneyV past 'an-open flue: damper. In such an installation the retention'of the mechanl` ical interlock between thev` damper and 'fuel valve maybe vhadby providing for delayed closure VVand preceding opening of thedamper relative to the' fuel valve, such as,'for example, by use of-a piston'j valve kinthe fuel linewliem a reciprocating Yt-,yp'el' partment and is intended to be connected to the combustion chamber of the furnace. The partition means |37 has a damper opening |38- therein providing communication between the compartments |35 and |33 and portions of that partitioning means circumambient of the damperopening may provide a downwardly-facing damper seat. An outside wall of the casing has a draft opening IIB therein, communicating withthe lead-in compartment |35, to serve as a draft relief and, as is usual in fuel oil installations and others where gases of combustion of fuel and fumes therefrom are obnoxious, such draft opening is provided with a gravity-biased pivoted butterfly plate |80 so pivotally mounted as to permit draft-relieving passage of air into thel chimney through that draft opening rather than up through the furnace appliance, but to prevent passage of gases from the furnace and its flue outward into surrounding air, as shown.

In the apparatus of Fig. 2 a laterally extending damper plate |20 is mounted upon the upper end of a lift-rod I2I which is slidably extended down through a hole |40 inthe bottom |39 of the casing' with that bottom structure thus serving as means for guiding the lift-rod in reciprocative movement, as does the bracket 39 of the structure of Fig. 1. The lift-rod I 2| is preferably made integral with a valve stem I3| and carries fixed thereto a pair of spaced-apart flanges orV plates" 45, between which is located the rounded ends of a fork on the end of operating arm |32 'of- 'a' motivating unit (not shown in this figure bu elsewhere depicted as in Fig. 6). `A piston valve II5, as shown in Fig'. 2, may7| comprise well-known structure having a casing provided with internally threaded inlet and outlet fittings 15| and |52 into which sections of fuel 'supply conduit I4 are anchored. .The fittings I5I and |52 have their inlet and outlet ports |53 and |54 communicating with a cylin-f' drical `chamber I 55 capped off at both ends by apertured caps |55 and |51 with the valve stem ISI slidably mounted through a gland onL cap .|56 in a substantially fluid-tight manner.v4 A cylindrical piston |29 is mounted on the lower'. end of the stem ISI and cosely fitted in chamal ber |55 for reciprocating movement therein. A by-pass pipe |58 connected into cap |5'l1 anda' side wall of the upper end of the casing I 59 connects both ends of the chamber |55 on opposite.

\ sides of piston |29 for the well-known purpose of relieving pressure to assure ease of operation of the piston valve. I

In operation of the apparatus shown in-Fig. 2,' with the damper plate |20 lifted to close damper'.

opening I 38 and the piston valve memberv |291y lifted to cut olf communication between inlet and outlet ports |53 and |54, when heat is demanded!- by a thermostatic control the motivating unitf4 operates arm 32 to lower the damper plate |20" and Fvalve member-|29 tothe positions-shown inf Fig. 2. Fuel -will then flow from inlet port V|53 through chamber |55 to outlet port |54 to be supplied to the burner in the combustion chamber of the furnace by conduit I4. Upon initial downward motion of the lift-rod |2| damper plate |23 will be immediately separated from its seat to uncover damper opening |38 to provideY communication between the flue inlet section |36 and flue outlet section |34. However, the valve ||5 will not be opened until'sometime later when the elongatedlpiston |29 thereof is finally lowered to a .position where its top end vbegins uncovering inletand outlet ports |53-and |54. Thus, opening of thedamper precedes opening of the fuel l valve and the damper plate 2|! `and the fuel valve piston |29 will eventually be lowered to the full opened positions shown in Fig. 2.

With the fuel valve IIE-open 'and the damper plate uncovering damper `opening |38 as shown in Fig. .2, gases of combustion will pass from inlet flue section i3d through leaddn comu partment |35, the damper opening |38 and outlet compartment |33 to exhaust -ue vsection |34 and .thence to the chimney. When sufficient heat has been supplied, Vas demanded `by Athe thermostatic control, the motivating `unit operating arm 32 will lift damper rod |2| and valve stem |3| so that the top .portion Vof the valve piston |29 will rstcover inlet and outlet ports |53 Vand :|54 of the vvalve .H5 thereby closing the latter and shutting off flow .of fuel to the burner while damper plate l1.2i! is still an appreciabledistance below its seat adjacent-damper opening |38. Further lifting of rod v12| and stem |3| will nallybring-the damper plate |20 up -to seating position to close .damper opening .|33

while maintaining the valve -|=|5 closed.

This delayed action of the apparatus shown in Fig. 2, i. e., opening of the damper |29 before opening of the fuel valve H5, assures -that as soon as fuel is supplied through the latter to theA burner resulting gases of combustion will be permitted to pass :through -the damper unit |9- to the chimney. Also upon Iclosing of 'the fuel valve ||5, the damper lI2() will remain open for ashorttime so that gases of combustion,`which may be still flowing from the combustion chamber, will be permitted to pass through thedamper opening ,|38 to thechimney. Then,after such time as will assure substantially complete eX-A haustionof ail gasesof combustionfnom the .combustion chamber through the damper .unit H9 tothe chimney, the damper 29 will be .closed with maintenance of vclosure of the fuel valve H5 .so thatl thereafter passage -of heated air through and from the furnace to the chimney will be prevented so'that heat will be conserved. Such action permits emcient employment 'of structure of the present invention in connection with the fuel burningheating devices.

.In Figs. 3, 4 and apreferred form of damper. unit is shown. This consists of a casing -2t9` formed by outsidewall means providing a chamber interiorly thereof which .in thecase of a gas furnace :has the bottom-thereof left -open at 2 3 to provide ya back draftdiverter opening. The interior of the casing 249 or the chamber there in is divided .into .an exhaustspace orcompartment y33 whichrcommunieates throughzan opening inthe avvall'or top ofthe c asingxwith. a section 34 ofthe flue pipe leading vto the chimney; and alead-in space or compartment 35 which com municates through an opening in -an vopposite wall ofthe casing with a section 35 .of flue pipe leadingsfrom-'thefurnaca Apartition .walkmeans 231z-n 'the .casing `defines the spaces or compartments .33 and 35 fronieach other and ir.isprm/ided with :a vdamper .opening |38 with the bottom face of .that wall adjacent the damper .opening providing a .damper seat -thereabout Suitable bracing means for reciprocatively guiding the lift-rod |.2| is mounted within the casing and may lcomprise -a bracketmember 239 secured at opposite ends to opposite outside walls of the casing in -the leadincompartment 35 and provided with an '.apertured guiding .boss 24B .vreciprocatively receiving the lift-rod |2'|.

The .upper-endpf the lift-rod |2I inthe struc, ture :shown rin Rigs. 3, v4 'and .5 rhas an abutment plate 4| securely mounted thereon and a damper platev22|l rests -upon the abutment with an aperture therein receiving the end Yof the lift-rod, although if `desired the damper plate may be xed to the lift-rod. A collar 42 mounted on the rod 12| above .the damper plate y22|) completes the ydirect connection between the latter and ithe lift-rod |2|. It will be noted from Figs. 3 and 5 that preferably the space between abutment plate -4| and :collar 42 is slightly greater than the thickness of thedamper plate 220 vand the'diameter of the aperture in the damper plate reeciving the end of ithe rod -is also preferably greater than the .diameter of the rod to provide for accurate seatingof :the damper plate against the seat of the wall 31 .about .the damper opening 38.

In'thestructure,shown in Figs. 3, 4 and 5 with the ue section 36.*conneeted .to the furnace and the flue section .34 connected Ito a chimney and with the fuel Valve :I5 in the fuel .conduit |4 closed as :Shown .in Fig. V3, the damper plate .22!)v will beheldby-the lift-rod |2| in closed position substantially to .block passage of combustion gases and Yheated air ,from the furnace to thegchimney and, inthe casefof gas fuel, these hot gases and relatively large `volumes of heated air will .be permitted to spill through the opening 2|8 into theroomin which the furnace iszinstalled. However, when the thermostat unit :25 demands more.

heat, -it initiates operation of the vmotor unit |22 causing the valve member 29 to be pushed away from'its-.seatpermittingflow of fuel to the burner, which .condition ;is :depicted in Fig. 5; and, at `the same time, the -end of the arm |32 is lowered forcing and/.or permitting the liftrodf|2|1and the damper plate 220 to move or-drop tothe open position permitting passagerof combustion gases from the .flue section `35 through the lead-in space 35, :damper opening |38, ,exhaust space 33 and the .iuexsection :34 tothe chimneyfas indicated .by the arrows. This direct mounting :of the damper vplate kon the operating member or 'lift-:rod :and `the rprovision for these members to fall by {forceof gravity to the open position have a vrmerit similar to that .z or .like characteristics 'of the structure shown in Fig. 2. Possibility of yfailureof connection to the damper plate substantially eliminated and'in the un' likely eventualty that :such 1failure does occur .the .damper will fail 4safe" l and likelihood of stickingfdue `eto -accumulative -or accidental presence of soot or foreign matter or objects is avoided.

In many .buildings r overhcad :boiler :room space is :restricted :and .for fthis reason vit rmay :be 1desirable to .-:mount the Avflue, sections leading -to and from "theLdamperu-nit i-inline. Such structures are proposed iin fFigs. f6, 7 rand 8. As shown'in Fig. :6, .the end of vthe fue section 34 leading to the V.chimneyy may be extended to within .they

4casing 219 and turned .downwardly at 43 to-provide the exhaust space or compartment 33. The lower end of the flue section 34 may be belled or flared outwardly such as at 44 about its open end 238 serving as a damper opening, to profvvide a seat for thev damper plate- 223 circumambient of the damper opening. The so-shaped end of the ue 34 also provides bafling which may be desired in the case of a chimney back draft in line mounting of the flue sections 34 and 36. The walls of the downturned end 43 of the flue section 311i also provide the partition wall means in the casing 2 I 9 defining the lead-in space or compartment 35 from the exhaust space or compartment 33 with the open end 233 of the flue section serving as the damper opening'in this wall means. Attention is particularly directed to the fact that in the structure proposed in Fig. 6 the liftrod l2| and the rod 3l connected lto the valve member 2S are made as an integral memberwith suitable spaced apart collars or plates A5, .45 mounted thereon to receive therebetween the end of the arm 32 of the motor unit 222. Thus there isa mechanical interlock between the valve me'mber 29 and the damper plate 22@ by means of direct connection of those two elements to a single rod l2l--3L This structure further eliminates possibility of unsafe failure of the flue-fuel controlV mechanism.

In Fig. 7 is shown a structure wherein similar in line mounting of the flue sections 34 and 35 had by providing a partition 33'! to define leadin space or compartment 35 and exhaust space or compartment 33 and with a portion thereof serving as a baffling as'indicated. Another pos-V sible modication of thefdamper unit of the pres ent invention is that shown in Fig. 8 wherein the end of the fiue section 34 is projected through a hole in a side wall of the casing 2 IS to form partition wall means dividing the casing chamber into exhaust space or compartment 33 andleadin space or compartment 35. -By cutting off the end of the pipe 34 at an angle to the vertical, such as 45, the resulting edge of the flue pipe provides a downwardly-facing damper seat about the open end thereof serving as a damper opening 338. In such case the damper plate 220 is angularly mounted directly on the lift-rod I 2l by suitably spaced apart collars or abutment members Illl and |42 having damper plate-engaging faces also angularly arranged as indicated. In this structure as in the modification shown in Figs. to 7, inclusive, the damper cpening'338 is substantially closed by lifting the damper plate 220 by means of the lift-rod l2! and is lowered to open position, shown in dotted lines in Fig. 8 by force of gravity or by rod IZI. Suitable baffling may be, if desired, provided at sie.

It will thus be seen by direct connection of the damper plate to its operting member and men chanical interlock between the damper and the fuel valve in addition t0 the other features of the invention described above that the indicated. opjects, notably safety, among others, are efciently attained. Wherever herein direct connection between the damper means or plate and its oper ating member and the fuel control means, or between other elements, is referred to, it is to be understood that indirect connection through intervening mechanism such as crank arms and additional linkage and bearings thereof is intended to be excluded.

Since certain changes may be made in the above construction and different embodiments of 1G lthe invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted asillustrative and not in a limiting sense. i

kIt is also to be understood that the following claims are intended to cover all of the generic and specific features of the invent-ion herein described as come within the scope of the appended claims, and all statements of the scope of the Ainvention which, as a matter of language, might be said to fall therebetween-- Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a control system for a furnace, a damper unit for the exhaust flue to be mounted therein between the furnace and a chimney exteriorly of the furnace comprising a casing having flue inlet and outlet openings` in side walls thereof at substantially the same level and the bottom thereof openfto provide a back draft diverter opening, wall means in said casing dening with the casing Walls an exhaust compartment in communication with the outlet opening and a lead-in compartment in communication with the inlet and diverter openings, said wall means having a damper opening therein providing communication between the compartments, said damper opening facing upstream of the passage for flow of gases through said unit from said flue inlet opening to said flue outlet opening, a substantially vertically disposed lift-rod, means-in said casing for guiding said lift-rod in reciprocative movement through the diverter opening, and a shut-off damper plate mounted directly onsaid lift-rod on the upstream side of said damper opening to be lifted thereby substantially to close the damper opening on its upstream side.

2. In a control system for a furnace, a damper unit for the exhaust flue to be mounted therein between the chimney and the furnace exteriorly of the latter comprising, in combination; a unitary casing structure distinct from any furnace structure and formed by outside wall means providing a chamber interiorly thereof; partition wall means in said casing structure dividing the chamber into an exhaust compartmentand a lead-in compartment; said outside wall means having an outlet opening communicating with the exhaust compartment and adapted for con# rection to an imperforate chimney fiue for passage of gases to the chimney only from the exhaust compartment, an inlet opening communicating with the lead-in compartment and adapted for connection to a, furnace exhaust flue, and a diverter opening in the bottom of said casing structure communicating with the lead-in compartment to provide a back draft diverter passage; a lift-rod; and means supported by said casing structure for guiding said lift-rod in up and down reciprocative movement through the diverter passage; said partition wall means including a downwardly facing damper seat circumambient of a damper opening for communication between the compartments, and a shutoff damper lift plate mounted directly on and carried by said lift-rodand adapted substantially to close the damper opening when lifted by said rod substantially into contact with said seat.

3. In a control system for a furnace, a damper unit for the exhaust flue to be mounted therein between the chimney and the furnace exteriorly of the latter comprising, in combination: a unitary casing structure distinct from any furnace Il structure and formed by outside wall means' providing a chamber interiorly thereof; partition Wall means in said casing structure dividing the chamber into an exhaust compartment and a lead-in compartment; said outside wall means having an outlet opening communicating with the exhaust compartment and adapted for connection to an imperforate chimney flue for passage of gases to the chimney only from the exhaust compartment, an inlet opening communieating with the lead-in compartment and adapted for connection to a furnace exhaust flue, and a diverter opening in the bottom of said casing communicating with the lead-in compartment; a substantially vertically disposed lift-rod pro'- jecting into said casing through the diverter opening; and means in said casing for guiding said lift-rod in reciprocative movement; said partition wall means having a damper opening' facing said lead-in compartment for downstream now of gases from the latter to said exhaust compartment, said partition wall means including a shut-01T damper lift plate mounted on the up-r stream side of said damper opening directly on and carried by" said lift-rod, said plate being adapted substantially to close the damper opening on its upstream side when lifted by said rod.

4. In a control system for a furnace, a fuel supply valve and damper assembly comprising, in combination: a unitary casing structure distinct from any furnace structure andV formed by out@ side' wall means providing a chamber interiorly thereof; partition wall means in said casing structure dividing the chamber into an exhaust compartment and a lead-in compartment; said outside wall means having an outlet opening communicating with the exhaust compartment and adapted for connection to an imperf'orate chimney nue for passage of gases to the chimney only from the exhaust compartment, an inlet opening communicating with the lead-in compartment and adapted for connection to a furnace exhaust ue, and a draft opening communicating with the lead-in compartment; a valve for a furnace fuel-supply conduit having a valve member; an automatically-controllable motivating unit connected to said valve member for moving the latter successively between an open position and a closed position; a substantially vertically disposed lift-rod connected directly to driven means of said motivating u-nit and extending directly to said casing and projecting into tlie latter through the bottom thereof; means supported by said casing for guiding said lift-rod in reciprocative movement; said' partition wall means having therein a damper opening facing said lead-in compartment for downstream new of gases from the latter to said exhaust compartment; and a shut-off damper lift plate mounted on the upstream side of said damper 'opening directly on and carried by said lift-rod and directly connected through said rod to the driven neans' of said motivating unitvand valve member, said lift-rod being so connected to the driven means of said motivating unit as' to cause it to lift said damper plate to a position substantially closing the damper opening on its upstream side when said valve member is moved from open position to closed position by said motivating unit,

5. In' a' control system for a furnacaa damper unit for the exhaust flue to be mounted therein between the furnace and a chimney exteriorly of thefurnace comprising a casing formed by outside Wall means having therein nue inlet and outlet openings and a draft opening lower than the inlet opening, partition wall means in said casig defining wil-h said outside wall means an exhau'st compartment in communication with the outlet opening and a lead-in compartment in communication with the inlet and draf openings, said partition wall means having therein a damper opening facing said lead-in compartment for downstream ow of gases from the latter to said exhaust compartment, a substantially vertically disposed lift-rod reciprocatively projecting into said casing through the bottom thereof, means for guiding said lift-rod in reciprocative movement through they casing bottom, and a shut-off damper plate mounted on the upstream side of said damper opening directly on said lift-rod to be lifted thereby substantially to close the damper' opening on its upstream side.

ALVA L. PALMER.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 66,326 Hadley L- g--- July 2, 1867 1,236,731 Martin t. Aug. 14, 1917 1,672,287 Travis f-- June 5, 1928 1,677,598 Resek July 17, 1928 2,037,363 Branche' Apr. 14, 1936 2,166,834 Wiltshire July 18, 1939 2,184,983 Tornquist Dec. 26, 1939 2,222,663 Handley Nov. 26, 19401 

